The US Environmental Protection Agency (EPA) released on December 19 the first-ever per- and polyfluoroalkyl substances (PFAS) water quality numerical limits for human health covering three PFAS—perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorobutanesulfonic acid (PFBS).
These non-enforceable numerical limits can be used by states and tribes to develop their own regulations under the Clean Water Act (CWA), such as water quality standards and wastewater discharge permits for inland and nearshore waters. The human health criteria are meant to protect the general population, including sensitive subgroups, when people engage in aquatic recreational activities such as swimming, wading, and fishing or shellfishing with the intent of consuming the catch.
Background
The process of developing the PFAS Human Health Criteria (HHC) is relatively new and was formulated as part of EPA’s PFAS Strategic Roadmap dating back to 2021. Initially, only PFOA and PFOS were considered for HHC development. The December 19 announcement extends HHC to include PFBS.
Under the CWA, HHC and Human Health Benchmarks indicate the maximum pollutant concentrations that can be in recreational water—as well as in fish and shellfish intended for human consumption—without having adverse effects on human health. EPA deemed the latter as requiring regulation given widespread PFAS detections in lakes, rivers, and oceans as well as in fish and shellfish. Moreover, EPA has determined PFOA and PFOS to be carcinogenic, necessitating conservative regulatory controls.
Specifics on Draft Human Health Water Quality Criteria
EPA’s factsheet contains the tabulated figures in Table 1. Two sets of values are provided depending on the exposure scenarios. Water and organism (WO) HCC apply to all water uses, including potable water, whereas organism only (OO) HCC apply to fishable water bodies without water supply intakes. EPA develops HCC solely based on science without regard for the feasibility of following these standards; some of the proposed limits are below the method detection limits (MDL) currently available from analytical methods such as EPA1633 (MDLs of 0.54 ng/L for PFOA, 0.63 ng/L for PFOS, and 0.37 ng/L for PFBS).
These numbers don’t account for the combined toxicity of co-occurring PFAS compounds. That will need to be addressed separately by applying established environmental risk assessment procedures when dealing with chemical mixtures. EPA suggests that PFAS act in a dose-additive manner.
Table 1. Draft Human Health Criteria for Three PFAS
| PFAS | Water+Organism HHC (ng/L; ppt)1 | Organism Only HHC (ng/L; ppt)1 |
| PFOA | 0.0009 | 0.00036 |
| PFOS | 0.06 | 0.07 |
| PFBS | 400 | 500 |
1 Values are provided in ng/L units to aid in comparison to MDL.
HCC account not only for water exposure scenarios, but also cancer/noncancer effects, catch consumption rates, amount of consumed water, bioaccumulation potential, as well as PFAS relative source contributions (RSC), such as regular diet, food packaging, consumer products, and contact with contaminated dust. EPA’s approach to calculating the HHC is conservative, with upper end limits in the 90th percentile assumed for key input parameters, such as water and catch consumption rates. The RSC is also conservatively set at 20%, meaning that 80% is reserved for other non-HCC sources of PFAS exposure.
What’s Next
The public comment period is set for 60 days upon publication of the HHC in the Federal Register. Like previous PFAS rulemaking, there will likely be extensive feedback, possibly resulting in changes to the proposed rule language.
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